In:
Canadian Journal of Forest Research, Canadian Science Publishing, Vol. 24, No. 7 ( 1994-07-01), p. 1464-1471
Abstract:
Branches on mature red spruce trees (Picearubens Sarg.) were fumigated with SO 2 in late summer of 1990 and 1991. There were four SO 2 treatment levels (0, 0.1, 0.2, and 0.4 ppm) and 12 fumigation chambers. Each treatment was replicated on three neighboring trees. Net photosynthesis and stomatal conductance of current-year foliage were determined with a Li-Cor photosynthesis system. Rates of foliar SO 2 absorption were estimated using regression models, with leaf temperature, relative humidity, atmospheric CO 2 concentrations, and photosynthetically active radiation as predictors. Fumigation effects became visible in terms of needle yellowing and browning after a few weeks of treatment. Effects on net photosynthesis and stomatal conductance were generally negative and in direct proportion with cumulative foliar SO 2 absorption. It was found that, in shade-adapted foliage, visible symptoms were delayed, and stomatal conductance was slightly stimulated at low SO 2 levels. In other foliage, leaf yellowing and browning occurred earlier, and stomatal conductance was depressed. Net photosynthesis was depressed at about the same rate regardless of branch position. Foliage subjected to high SO 2 concentration treatments did not recover from SO 2 damage 1 year after treatment: needles had fallen off the twigs, and needle and twig length of new foliage was reduced.
Type of Medium:
Online Resource
ISSN:
0045-5067
,
1208-6037
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
1994
detail.hit.zdb_id:
1473096-0
SSG:
23
SSG:
12
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